Polycarbonates are well-known, commercially available materials which have achieved wide acceptance in the plastics industry. Generally speaking, such polymers exhibit excellent properties of toughness, flexibility, tensile strength, dimensional stability and impact strength surpassing that of many other thermoplastic materials.
Such polymers are prepared by reacting a carbonate precursor, such as phosgene, for example, with a dihydric phenol, such as 2,2-bis(4-hydroxyphenyl)propane, herein refered to as "bisphenol-A," to provide a linear polymer consisting of dihydric phenol units bonded to one another through carbonate linkages.
The dihydric phenols, in turn, are prepared by the reaction of a phenol with a carbonyl compound, usually ketone or aldehyde, and usually in the presence of acids.